Import of multiple domains from Delft3D

I am trying to import multiple domains from Delft3D into EFDC. In Delft3D these domains were connected using DD boundaries, creating one large grid. When trying to import these domains into EFDC it seems I can only load one GRD file at a time. Selecting the “Check for Disconnected Sub-Domains” does not seem to help as I can’t seem to specify the DD boundaries from Delft, which informs the program how the domains are connected. When one domain has been loaded I don’t seem to be able to load another one as my only option seems to be to generate a new EFDC model. The only option I can think of would be to paste my domains together in Delft and load one large grid into EFDC. However, this would pose serious problems for me as I have 1-3 ratios between several domains.
Is there a way to load several domains into EFDC and then connect them?

Thanks for your help.


Please refer to this thread. {REMOVED by Admin} Thanks. John

Hello John,
Thanks for your reply. I have read the thread you referred to and it does not explain in detail how multiple domains are imported. I’m only able to load one domain during the grid generation step. Furthermore, after I have imported a grid and saved the project the MAPGNS file is not generated in the directory with the files for the new model.
Please let me know how you generate the MAPGNS file and what are the steps needed to import multiple domains.




I haven’t tried this myself but what I did was to join the separate domains in delft3d RGFgrid one by one. So if you have 4 domains first load 2 then paste these and make one and then add another and so on. At last you will have only one grid which you can then import into EFDC Explorer. I also tried to do in EFDC Explorer but it is little complex as you said. I will look into it and will share information if I find out a way.


Thanks for checking into this. I don’t think joining my grids together is a feasible option for my application so if you find another option, please let me know.


We have created a short guidance document on this topic, “2013_01 Importing Multiple Grids into EE7”. Please view it under “Documents”, “Guidance” and let us know if you have further questions:

I recently found out that EFDC explorer 6 has an capability to import multiple grids for Delft RGFgrid. There is an option labeled “Check for Disconnected Sub-Domains”. I was playing with this option and I find this really interesting. However, the difficulty I encounter is I was not able to combine these as a single grid. Even if I was able to import all the grids to the EFDC model it seems there are still displayed as different subdomains. I checked the USER’s manual and it say MAPGNS file stores the various sub-domains. I was not able to see this mapgns file and then post-process the grid to allow non-adjoining cells to connect.

Any help is highly appreciable.



I didn’t find information on how to connect these grids on the EFDC Explorer. However, an alternative approach would be to paste all the grids in the DELFT RGFGRID and make a single grid and import into EFDC Explorer. Some difficulties may arise while pasting two grids of variable grid size so I would suggest to make the ends i.e boundaries of same size and then paste the grid. Minor editing can be done later.

I would however, like to know how does EFDC Explorer handle such cases.



Thanks for your question John. Once the DELFT3D model grid is imported, EE keeps each sub-domain in an isolated section in the IJ space. The user must then manually connect each sub-domain using the MAPGNS file. EE has a point & click feature to define the linkages. Once the model is saved, the MAPGNS file is created and EFDC will allow flows between the sub-domains.

Please note that we will be releasing a grid generating tool in the next couple of months. It will have similar capabilities to RGFGRID.